Telephone line with one-way repeater



Patented Aug. 10, 1926.

I UNITED STATES lremerci* OFFICE..

WILHELM OHNEVSORGE, 0F DORTMUND, GEBHNY, ASSIG'NOR T0 SIEMENS mmAKTIENGESELLSCHAFT, DI' SIEMENSSTADT, NEAR BERLIN, GERMANY, A COB-roraarron or unaniem?.V

TELEPHONE LINE 'WITH ONE-WAY BEPEATEB.

Application filed' August 23, 1,921, Serial No. 494,569, and in GermanyDecember 16, 1915.

(crumb 'annex'. rm: rnovrsrons or m or or innen s, 1921, 41 sur. L.,131s.)

For improving the transmission of speech and extending the range oftelephonie communications repeaters are generally used which areinserted into the line for amplify- 5 ing the speakingcurrents. Themethods of i inserting; the repeaters in the line are commoniliT basedupon the differential or bridge circuit principle, which has however theinconvenience that the effect of the repeater is 10 considerably reducedon account of the subdivision of the output current.l For pre--` ventingsinging the two sections of the line must have approximately the sameelectrical characteristics. The electrical character l5 istics varyhowever continuously in each section of the line so that singingfrequently occurs. But before the singing begins the speech maybealready distorted or become unintelligible on account of theinterference 2U by natural. oscillations.

f For preventing these troubles two two wire-circuits hare already beenused withl one way repeaters in cach circuit so that in each line onlythe current flowing in one 25 direction is amplified. But this systemhas the inconvenience that the connection of such a four wire circuitwith the ends of a two wire line is not possible. Without this con-4nection the four Wire system has however no 3U practical value. as allthe'telephonic installations actually in use are designed for two wirecircuits.

The present invention consists'in a method 'for obriating thesedifficulties and allowing 55- the connection of such a four wire circuitto the end of a two wire line'of usual design. An arrangement accordingto the invention F is shown on the drawing.

The accompanying drawingr represents a l diagram `of a four wire circuitarranged ac-y cardiner to my invention. B v the four wire circuit whichconsists of two wire circuits V and lll. talking" in both directions ispossible. Through the two wire circuit V speech cur- 5 vente aretransmittedA from the left to ,the right hand in the drawing and throughthe two wire circuits W in the opposite direction, Two wire circuits aand b are/ connect'cd to the two long distance wire circuits w 4V and Wby means of a` `W'heatstone bridge and in the long distance circuitsVandl W arel inserted repeaters R, and 1L. respectively. 1

Tolhe opposite points/g, h; k, i r

tively i'mn; 0, Z of two Wheatstone bri ges' 55 l A andB are connectedthe ends of the long clistarice twowirc lines V1 W forming togethera fhrwire line. Two of the branches of cach'Wheatstone bridge contain each atransformer winding! c, d; e, f, the other M branches contain each thehalf of a coil p, q. The winding I of the transformer d is connccted tothe ends of the` two wire line b (distance or subscribers line).y whilethe windingr I of the transformer r; is connected n with an iertificialbalancing line w. llf the subscribcrs line and the artificial line4 arewell balanced the talking current transmitted by the line V to thepointez', 'k of 'the bridge is subdivided in such a manner that 'm nocurrent passes to the line W connected to the points g, l, of thebridge. The current circuit of the bridge is closed without attenuationover the two other branches of the coil q of the bridge. The coil qconsists'of two 'la halves marked q. qu in the right hand portion of thefigure and is bifilarly wound upon itel iron core in such manner thatwhen the cui-y rent flows in parallel through the two halves-i. e. fromthe point i towards the su two outer ends g and u-only ohrnic resistanceis offered to the current, because in that: case the currents flow' inopposite direction from the center towards the outer ends and thus theirinductive effects neutralize each filli- 'other. By the transformer dthe talking currents are transmitted inductively to the subscribers lineb. If the speech is to be transmitted from the subecribers line to thefour wire circuit the current induced in the un winding II by lthewinding I of the transformer d ilows principally through the winding IIof the coil c of the balancing" line :c and the long distance line W, asthe4 coil g of the bridge interposes in this case a W This has beenconfirmed practical experiments. F or compensating.,r the losses andfurthermore obtainingr any desired amplifiration repeaters niay beinserted at the ends of 'the line Y and W. lthe effect of which may beadapted in a known manner to the two wire line by adjustableresistances. A niutual reaction between the repeaters arranged at theends and in the. middle of the four wire circuit cannot occur as onaccount of the bridge no or onlia very Sinall current is flowing' fromthe line Y into the line lV. By means of this method in connection withthe lone' distance four wire line provided with one way repeaters atconvenient points langes of communication ot any distance :5000 kin. andmore) are obtainable..

llavinfr now particularly `described and ascertained the nature of my.said invention and in what manner the saine is to be per formed, ldeclare that what l claiin is:-

1. A telephone s t'steni havingr in combination a tour wire circuitconsistiirgr of a separate two wire long distance circuit for eachdirectionl` a one way repeater in each of Said loner distance lines. anartificial balance line` a lVheatstone bridge at the ends of said longdistance lines to opposite points of which are connected the ends ot'the loner distance lines, a transformer for each of two adjacentbranches of each bridge, said transformers having one of their windingsin circuit with their pertaining branch and having the other windingsconnected respectively to a two wire line and to said artificial balanceline.

2i A telephone system havin);Y in combination a fonr wire circuitconsisting of separate tno wire long distance lines fon each talkin;rdirection. a one way repeater in each of said longr distance lines. anartificial bal ance line` a Wheatstone bridge at the ends of said lonedistance lines to opposite points ot which are conne -ted the ends ofthe lon; r distance lines. a transformer `for each ot' two adjacentbranches of each bridge. said transformers having one of their windingsin circuit with their pertaining branch and having: the other \\indinfsconnected rcspcctively to a two wire line and to said artificial balanceline` an indnetance interposed in cach of thc two other adjacent.branches of the aid 'heatst'one bridges and allowing the transfer of thetelephonie currents. front the connected two wire cir cuit. into one ot'the lon;r distance lilies while preventing the transfer to the otherloner distance line.

ln testimonv wlicrcotl l affix in)- signature.

